The purpose of this project is to delineate the physico-chemical mechanism(s) of lens protein interaction and aggregation and thereby to gain insight into the etiology of human senile cataracts. The formation of macromolecular bovine low MW alpha-crystallin from its subunit polypeptides has been studied as a model system employing the method of chemical modification. The methods of solvent and temperature perturbation employed in conjunction with chemical modification will be used to elucidate the mechanism(s) of the complex(es) formation and/or clustering of soluble crystallins. Isolation of these crystallin interactions and complexes will be undertaken employing various chromatographic procedures. Characterization using ultracentrifugation and spectrascopy will establish whether or not the crystallin complexe(s) is due to alter protein-protein or protein-small MW compounds interaction or both. Information thus obtained shall be be valuable in delineating the mechanism of lens opacification in human senile cataractogenesis.